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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Intensive care medicine 2 (1976), S. 3-6 
    ISSN: 1432-1238
    Keywords: Impedance cardiogram ; Cardiac output ; Stroke volume ; Averaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In six volunteers (5 male, 1 female) it has been shown that normal respiration made no statistical difference to the estimates of the mean stroke volume and the mean cardiac output as determined by the electrical impedance method of Kubiceket al, (1966). The coefficient of variation was usually increased by respiration. The use of those stroke volumes which occur only at end-expiration was not shown to yield a greater reproducibility with 3 other male volunteers. In the female subject it was found that the use of a digital averager triggered from the preceding R-wave of the ECG gave values for the mean stroke volume and cardiac output which were always lower than the conventional mean values obtained from a number of strokes. The expense of either of these approaches does not appear to be justified as a means of compensating for the effects of normal respiration on the impedance dZ/dt waveform.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water-soluble, random copolymers containing L-methionine and N5-(3-hydroxypropyl)-L-glutamine have been prepared, fractionated, and characterized. The thermally induced helix-coil transitions of these copolymers in water have been investigated, and it has been found that incorporation of L-methionine increases the helix content of the polymers at all temperatures in the range of 0-60°C. The Zimm-Bragg parameters σ and s for the helix-coil transition in poly(L-methionine) in water were deduced from an analysis of the melting curves of the copolymers using the methods described in earlier papers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previously used procedures for processing the amino acids from 6N hydrochloric acid hydrolysis of poly[N5-(4-hydroxybutyl)-L-glutamine], poly[N5-(3-hydroxypropyl)-L-glutamine], and several random copolymers derived from these, led to the formation of spurious products. These have been isolated and characterized as the γ-ester of glutamic acid and the hydroxyalkyl amine, and chloro-alkyl amine hydrochloride. The former reduces the observed values for glutamic acid, but the latter has no effect on them. A method is used to avoid formation of these artifacts in the amino-acid analysis. Of all the copolymers studied previously in this series, the compositions of only those containing L-serine are in error as a result of the formation of the γ-ester. A redetermination of the amino-acid compositions of the copolymer fractions studied earlier leads to slightly revised values for the Zimm-Bragg parameters σ and s of serine.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 182-186 
    ISSN: 1741-0444
    Keywords: Blood resistivity ; Electrical impedance ; Cardiac output
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Pour pouvoir appliquer la méthode de l'impédance électrique pour la mesure du débit sanguin chez des patients à l'hémodialyse où l'on peut rencontrer use vaste gamme d'hématocrites, il est nécessaire d'avoir des connaissances sur la relation entre la résistivité et l'hématocrite du sang. Une relation linéaire optimale a été déterminée pour le sang humain à 37°C et 100 kHz sur la gamme d'hématocrites de 14 à 45%.
    Abstract: Zusammenfassung Um die elektrische Impedanzmethode zur Messung der Herzleistung bei Patienten anwenden zu können, die durch Blutidialyse behandelt werden, wo ein breiterer Bereich von Blutzentrifugenwerten angetroffen werden kann, ist die Kenntnis des Verhältnisses zwischen dem spezifischen Widerstand des Blutes und dem Blutzentrifugenwert enforderlich. Es wurde ein Verhältnis nach der linearen Methode der kleisten Quadrate für das menschliche Blut bei 37°C und 100 kHz über einen Blutzentrifugenwertbereich von 14 bis 45% bestimmt.
    Notes: Abstract In order to be able to employ the electrical-impedance method for the measurement of cardiac output in patients on haemodialysis where a wide range of haematocrits may be encountered, a knowledge of the relationship between the resistivity and haematocrit of blood is required. A linear least-squares relationship has been determined for human blood at 37°C and 100 kHz over the haematocrit range from 14 to 45%
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 14 (1976), S. 74-78 
    ISSN: 1741-0444
    Keywords: Impedance cardiograph ; Analogue computer ; Stroke volume ; Cardiac output
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire L'article décrit un circuit analogue servant à mesurer les volumes de battement pour usage en conjonction avec l'e.c.g.dZ/dt et les signaux phonocardiogrammes produits par un cardiographe d'impédance IFM. L'affichage est effectué sur un cadran numérique. Ce circuit peut être étendu pour mesurer le rendement cardiaque.
    Abstract: Zussammenfassung Es wird eine Analogschaltung zum Einsatz in Verbindung mit dendZ/dt-, e.k.g.-und Phonokardiogrammsignalen von einem IFM-Impedanz-Kardiographen zur Messung des Hubvolumens beschrieben. Die Anzeige erfolgt auf einem digitalen Meßgerät. Die Schaltung kann zur Messung der Herzleistung erweitert werden.
    Notes: Abstract An analogue circuit is described for use in conjunction with thedZ/dt, e.c.g. and phonocardiogram signals from an IFM Impedance Cardiograph to measure stroke volume. This is displayed on a digital meter. The circuit can be extended to measure cardiac output.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 187-191 
    ISSN: 1741-0444
    Keywords: Cardiac output ; Electrical impedance ; Radiocardiogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Vingt paires simultanées de valeurs de débit sanguin en provenance de patients ne présentant pas d'anormalités valvulaires ont été obtenues par la méthode radio-isotopique et la méthode d'impédance életrique deKubicek et al (1966). Si on a admis pour la résistité sanguine de chaque patient une valeur-type de 150Ω, la valeur d'impédance moyenne de débit sanguin était supérieure de 14·5% par rappórt à la valeur radio-isotopique moyenne. Dans la présente étude, les hématocrites des patients s'échelonnaient de 20 à 48%. En faisant passer la valeur de résistivité appropriée pour chaque patient dans l'équation de volume d'apoplexie de Kubicek à partir des données de Geddes et de Sadler (1973), on obtient une valeur d'impédance moyenne inférieure de 10·3% par rapport à la valeur isotopique moyenne. L'utilisation de nos données de résistivité mesurées ont amené la valeur d'impédance moyenne de débit sanguin à 21·5% au-dessous de la valeur isotopique moyenne. Le coefficient de corrélation entre les techniques à impédance et les techniques à isotopes était de 0·61 pour la valeur-type de résistivité de 150Ωcm. Ce coefficient a été amené à 0.87 par l'utilisation des données de résistivité de Geddes et Sadler (1973), contre 0·88 avec nos données.
    Abstract: Zusammenfassung Zwanzig simultane Herzleistungspaarwerte von Patienten ohne Herzklappen-Anomalitäten wurden durch das Radioisotopenverfahren und das elektrische Impedanzverfahren von Kubicek und anderen (1966) erhalten. Wenn ein Standardwert von 150Ωcm für den spezifischen Widerstand des Blutes eines jeden Patienten angenommen wurde, betrug der Durchschnittswert für die Impedanz-herzleistung 14·5%, was im Vergleich zum durchschnittlichen Radioisotopenwert hoch ist. In dieser Untersuchung lagen die Blutzentrifugenwerte der Patienten zwischen 20 and 48%. Wenn man den entsprechenden spezifischen Widerstandswert für jeden Patienten in die Hubvolumengleichung von Kubicek aus den Daten nach Geddes und Sadler (1973) eisetzt, ist der mittlere Impedanzwert von 10·3% im Vergleich zum mittleren Isotopenwert niedrig. Bei Anwendung unserer gemessenen Widerstandsdaten lag der mittlere Herzleistungs-impedanzwert um 21·5% unter dem mittleren Isotopenwert. Der Korrelationskoeffizient zwischen Impedanz-und Isotopen-technik betrug 0·61 für den Standard-Widerstandswert von 150Ωcm. Bei Verwendung der Widerstandsdaten nach Geddes und Sadler (1973) betrug der Korrelationskoeffizient 0·87 mit unseren Daten 0·88.
    Notes: Abstract Twenty simultaneous pairs of cardiac output values from patients who did not have valvular abnormalities were obtained by the radioisotope method and the electrical-impedance method of Kubicek et al. (1966). If a standard value of 150Ω-cm was assumed for the resistivity of each patient's blood, the mean value for the impedance cardiac output was 14·5% high compared with the mean radioisotope value. In this study the patient's haematocrits ranged from 20 to 48%. Inserting the appropriate value of the resistivity for each patient into the stroke volume equation of Kubicek from the data of Geddes and Sadler (1973) made the mean impedance value 10·3% low compared with the mean isotope value. The use of our measured resistivity data made the mean impedance cardiac output value 21·5% lower than the mean isotope value. The correlation coefficient between the impedance and isotope techniques was 0·61 for the standard value of resistivity of 150Ω-cm. Using the resistivity data of Geddes and Sadler (1973) the correlation became 0·87, and with our data it was 0·88.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 851-863 
    ISSN: 0887-624X
    Keywords: polymerization ; kinetics ; free radical ; transfer ; photolysis ; propagation ; rate coefficients ; termination ; EPR ; copolymerization ; initiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problems of determining reliable, well-characterized values of kinetic parameters in free-radical polymerizations are discussed. The origins of the fact that experimental determinations of rate coefficients of ostensibly identical systems often result in quite different values being reported can be ascribed to subtle mechanistic assumptions made in data interpretation, which are considered in detail. A series of recommendations to assist in overcoming these problems, and to highlight their origins, are presented, with emphasis placed on new techniques including those employing laser photolysis and EPR.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2439-2454 
    ISSN: 0887-624X
    Keywords: radiation ; nitrile rubber ; NMR ; ESR ; radicals ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of radiation-induced structural changes in nitrile rubber with different acrylonitrile contents were investigated by ESR, NMR, and FTIR. To investigate new structures solid-state NMR methods had to be used due to crosslinking of the irradiated rubbers, and higher probe temperatures were used to obtain better resolution. The radicals generated on the acrylonitrile groups were found to abstract hydrogen from the adjacent butadiene units resulting in the formation of allylic radicals. These allylic radicals reacted to form intermolecular crosslinks and cyclisation. Cyclisation of the butadiene units were found to occur in the initial stages of the irradiation. Radiation yields of radicals increased with acrylonitrile content from 1.42, 1.58, to 2.42 for 18, 30, and 45% acrylonitrile rubbers. The radiation yields for intermolecular crosslinking were higher in rubbers with higher acrylonitrile contents, giving G values of 17.8, 21.3, and 24.5 for 18, 30, and 45% acrylonitrile rubbers, respectively. However, the crosslink clustering was found to be less in the rubbers with a higher acrylonitrile content. © 1996 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2469-2480 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amino-acid-sequence distribution in poly(γ-benzyl-L-glutamate, L-methionine) prepared by polymerization of the respective N-carboxyanhydrides has been investigated. This copolymer was converted first to poly(L-glutamic acid, L-methionine), which was subsequently cleaved by treatment with cyanogen bromide. The resulting material was fractionated into oligomers of (glutamic acid)n-homoserine whose relative molar amounts were determined quantitatively. The results have been compared with those for a random incorporation of the methionine in a γ-benzylglutamate host polymer. Fairly close agreement has been found.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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